The present invention relates to irrigation sprinklers, and more particularly, to an improved containment ring for pop-up sprinklers.
Pop-up sprinklers are widely used in both residential and commercial applications to irrigate lawns and shrubs. They typically include a tubular riser that is axially retracted into a fixed cylindrical outer housing buried in the ground when not in use, and which extends from the cylindrical outer housing to a position above the surface of the ground when water pressure is applied. The top of the riser is level with the ground when retracted. A coil spring surrounds the riser within the cylindrical outer housing and retracts the riser when the water source to the sprinkler is shut off. The upper end of the coil spring is held in place by a containment ring that seats against a shoulder at the upper end of the cylindrical outer housing.
In many applications of pop-up sprinklers, such as playing fields, golf courses and the like, it is important that the tops of the risers of the sprinklers reliably retract to a position level with the surface of the playing field, so that they do not become obstacles. However, the typical riser of a conventional pop-up sprinkler frequently jams or sticks in a partially retracted position. This usually occurs when dirt and/or other debris get into the cylindrical housing between the containment ring and the riser.
In a conventional pop-up sprinkler the riser and its retraction spring are assembled into the fixed outer housing from the top. These components are typically retained in place by a substantially rigid hard plastic containment spring which snaps into an annular groove at the top of the fixed outer housing. The containment ring is split so that it can be compressed inward in diameter and inserted into the upper end of the bore of the fixed outer cylindrical housing. The containment ring is then allowed to expand to engage in the annular groove in the outer housing bore to retain the riser in the housing. The containment ring has a sufficient gap at its split to enable the ring to be radially compressed sufficiently to be inserted into the bore of the outer housing. When the containment ring expands into the annular groove, the vertical opposing faces or ends of the ring spread apart, leaving a gap which allows dirt and/or other debris to enter the cylindrical outer housing. This can cause the riser to jam in extended position.
It would be undesirable to utilize a rigid plastic split ring with a separate underlying elastomeric washer as a seal to prevent the entry of debris. This is because customers who must remove the riser for servicing would have a great deal of difficulty reinstalling an elastomeric washer and a separate rigid split containment ring.
It is, therefore, desirable that an improved containment ring be available to hold a riser retraction spring inside the fixed outer housing of a pop-up sprinkler that would reduce the entry of dirt and/or other debris into the outer housing of the sprinkler.